Electrical heating apparatus



Feb. 10, 1953 c. E. WELLER 3, 9 ELECTR ICAL HEATING APPARATUS Original Filed July 14, 1941 2 SHEETSSHEET 1 GOO GOO

INVENTOR ATTORNEYS Reissues! Feb. 10, 1953 ELECTRICAL HEATING APPARATUS Carl E. Weller, Easton, Pa., assignor to Weller Manufacturing Company, Boston, Pa., a limited partnership of Pennsylvania Original No. 2,405,866, dated August 13, 1948, 80- rial No. 402,372, July 14, 1941. Application for reissue July 10, 1952, Serial No. 298,219

11 Claims. (Cl. 21926) Matter enclosed in heavybrackets 1 appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to electrically heated apparatus and more particularly to electrically heated soldering apparatus for intermittent use.

An object of the invention is to provide an electrically heated apparatus which will be simple and durable in construction, convenient in desi n and efficient and economical in operation.

Another object of the invention is to provide in a soldering'iron an easily tinnable tip which may be heated quickly and with a minimum current consumption.

Another object of the invention is to provide a well ventilated soldering iron to the end that the heat of frequent intermittent or long continued use will be advantageously rapidly conducted away from the leads of the iron.

Another object of the invention is to provide in an electric soldering iron a control switch of convenient and efilcient design.

The invention contemplates a soldering iron of pistol-grip typ having a readily renewable tinned copper tip at one end. a finger-actuated control switch comprising toggle and spring lever elements at the other end, and an intermediate step-down transformer unit, the whole characterized by perforated sheet metal ventilatin shield for cooling the tip and transformer.

The invention will be readily understood by referring to the following detailed specification including the several drawings forming part thereof, wherein Fig. 1 shows in side elevation the exterior of an electric soldering iron constituting a preferred embodiment of the invention;

Fig. 2 is a top plan view of the iron shown in Fig. 1; I

Fig. 3 is a side sectional view corresponding to Fig. l but showing portions removed to illustrate the interior disposition of the elements;

Fig. 4 is a section taken on the line 4-4, of Fi 'Fig. 5 is an enlarged sectional view, fragmentarily showing the frontal tipmounting; and

Fig. 6 is a detail perspective of a tinned copper tip.

Referring to the drawings wherein identical parts are indicated by similar reference numerals,

ment the primary winding It Frame it includes opposite ends II-ll top It and bottom is, the laminae being assembled by spaced corner bolts 20, II tightened by nuts 2|. 2|. Top and bottom portions of frame llinclude vertical slots 23-23 for receiving bolts 24. Primary winding It of the transformer is designed a cludes 880 turns of #27 wire while secondary ding consists of 2 turns of #5 B. t: 8. gauge.

Shielding II for ventilating and dissipating heat is preferably of sheet copper which, for example, may be .025 inch in thickness. The shielding includes an upper hood SI of elongated form .having lower straight edges 32 and a number of a step-down transformer It is enclosed by shielding ll carrying at the f rward end tip I! and at the other end handle i containing switch it.

Transformer in includes'a rectangular frame It of laminated iron which may be of any desirable dimension and construction. It has been found convenient to employ for this purpose one inch scrapless punching and stacked inch steel.

perforations 31 disposed therealong in order to insure full ventilation. The hood is closed rearwardly with a plate is andther'ebelow connects with opposite curved side plates 35 and It having parallel upper and lower flanges 11. Holes II in said flanges receive bolts 20 fitted with outer nuts 39. By referring to Fig.4 it will be observed that the side plates are assembled on the laminated core or frame and within the parallel edges 32 of the upper hood and spaced from said hood by insulation elements ll. Curved side plates SI. 36 are provided with a plurality of spaced perforatlons arranged, for example, in upper and I lower rows for ventilation.

The tip 12 of the soldering iron constitutes a forward extension [ll] of the secondary leads 43, such forward extensions being closely engaged by a forward retaining wall It. Retaining wall 4| is preferably of porcelain or asbestos and it will be observed that its design assists in conducting heat away from the leads to the ventilating shield. as well as preventing heat from developing rearward thereof. While the invention, of course. is

not limited to the use of asbestos or porcelain, in this connection it is desirable that the material constituting wall ll be a good heat conductor and insulator. Wall 4! has opposite parallel sides It and a curved top l'l fitting within ventilating hood Ii. Wall 45 [bottom ll] has a transverse recess 48 [48a] aligning with opposite holes b in shield edges 12 for receiving a headed bolt I.

' assembled therein and tightened by nut a.

Well 45 is provided with equally spaced parallel holes 50iil for receiving each a plug Ii. Plug Ii 3 in turn is provided with a recess Ila to receive externally threaded plug it. The opposite face of plug 5| has recess I in which the extremity of secondary lead It is intimately engaged. A radial hole I! drilled in the forward portion of plug II is aligned with axial recess II for tightly securing tip I! when the externally threaded plug it is tightened. Plug 62 has an hexagonal head I! for ready plier or wrench turning. Tip I! it will be observed, constitutes a shunt conductor across the secondary winding, the V-shaped extremity 60 being tirmed and diverging shanks II and Ila having upturned rearward extremities 62 and 62a fixed in radial holes 55-".

Handle It includes aluminum castings 84 comprising top 65 and bottom 86, the intumed edges of each casting abutting to provide suitable switch storage space, the handle being assembled by rivets or screws 81. Handle sections it include extensions 89 at the top having suitable holes for receiving the lower assembly bolts -24 [2ll20]. Each castingis recessed forwardly at III in order to provide vertical slot II for receiving finger-actuated trigger l2.

Desirable intermittent operation of the soldering iron is very conveniently obtained by inward and outward movement of trigger 12, the same being pivotally mounted on pins ll fixed in the opposite castings. The trigger has a curved forward face for comfortably accommodating the operators finger at the grip and a lower straight edge 11 having a socket .II in which is mounted ball head I! of switch It. At the rearward and trigger it has recess 80 for receiving one end of tension spring 8|, th other end of the spring being fast in fixed bracket 83, see Fig. 3. It will be observed the tension of the spring II is such as normally to thrust trigger it outwardly, thus 'opening switch II, the current being normally cut oil. In operation the soldering iron is heated by tightening the finger grip on the trigger l2, pulling the latter against the spring tension and causing current to flow through the transformer and rapidly heat the tip I2. when the pressure on the trigger is released, spring Bl throws the trigger forwardly and reopens the switch, thus cutting off the flow of current to the tip.

The high current of approximately 200 amperes flowing through the secondary comprising the secondary winding and copper tip 12 produces rapid heating in the tip 12 because of the pronouncedly smaller cross section of the tip. Heating in the secondary winding 30 and the forward extensions 43 thereof is minimize because of their relatively large cross section. It will be observed that the divergent shanks 61 and 61a of the small cross section copper tip 12 impede the flow of heat from the outer extremity 60 o/ thejtip to the secondary extensions 43 because 0) the substantial thermal resistance of the shanks 61 and 61a, while the larger cross section extensions 43 serve to rapidly dissipate the heat generated in the shanks 61 and 61a of the tip 12, thus maintaining the outer extremity 60 at a relatively higher temperature than the shanks. Since the copper material of the tip inherently has a high temperature ooefilcient of resistance, the higher temperature of the outer extremity 60 increases its resistance relative to that of the sh nks 61 and 61a, thereby increasing the speed of heating at the outer extremity 60 and provid ing the greatest heat at this point where it'is readily accessible for delivery to the work.

It will likewise be observed that the reduction in the temperature of the outer ex remity 60 of 4 the tip 12, when the tip is placed in contact with the work to be soldered and heat is drained therefrom into the work, produces a proportional feduction in the resistance of this outer extremity region 60, thereby increasing the power delivered to the secondary circuit and the speed of heating of the tip. Since this highly heated portion is confined to a small section of the tip at the outer extremity 60 thereof and therefore has a low thermal storage capacity, this adiustment in resistance and power delivered to the tip when the tip contacts the work is quite rapid.

From the foregoing it will be observed that the conventional alloy tips are dispensed with. By substituting copper wire for alloy tips tinning of the tip is facilitated. The copper material of the tips is quite cheap and deterioration is readily corrected by replacing the tip. Replacement of a copper tip is easily accomplished since it is necessary only to loosen plugs II and withdraw the old copper tip. The ends of the new copper tip may then be inserted through axial bore 58, the turned up ends it and Ila being then rigidly tightened into position by taking up on plugs 52, the soldering iron being thus almost instantly ready for use. Preferably the secondary winding at the transformer side of wall II is much heavier thanthewireoftipll. I

The automatic cut-of! switch assembly II is desirable to insure safetywhile the reduction from enerator to tinned tip insures a considerable saving of time and current inintermittent' operation.

It will be understood that the specific details of construction set forth hereinabove describe merely one preferred form of the invention which is capable of many other modifications; hence the invention is not to be limited other than by the spirit and scope of the appended claims.

What is claimed is:

1. An electrical heatingapparatus comprising a quick-heating soldering iron including a stepdown transformer having primary and secondary [turns] windings, said secondary [turnsJwinding being of pronouncedly greater cross-sectional area than said primary [turns] winding, and a detachable heating tip o]v a highly electrically and thermally conductive readily tinnable material rigidly mounted and held tightly in electrical communication [with] across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area than the secondary detachable soldering tip electrically to communi-v 'cate with the secondary winding.

3. An electrical heating apparatus comprising a quick-heating soldering iron including a stepdown transformer having primary and secondary turns, said secondary turns being of pronouncedly greater cross-sectional area than said primary turns, a detachable tinnable copper heating tip rigidly mounted and held tightly in electrical communication with the secondary winding,

= spaced integral oflset portions on said tip, said tinn'able copper tip being oi pronouncedly smaller cross-sectional area than said secondary winding, spaced fixed plugs maintained tightly in electrical communication with the ends otthe secondary winding and each having a transverse recess tor receiving an oflset portion of the tip.

and threaded take-up means in each plug for r rigidly mounting the tip therein.

4. A quick-heating soldering iron having spaced end portions, a center portion therebetween, a step-down transformer having primary and secondary windings in the center portion, a pistol-grip containing an ofl-on trigger switch on one or said end portions, said switch for controlling said transformer, spaced secondary winding extensions fixed in the other of said end portions, and a detachable substantially V-shaped copper wire heating tip held tightly in electrical communication with the secondary winding extrical communication across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area throughout than the thereinduring soldering. I

tensions and projecting from the last-mentioned end portion, said heating tip being of pronouncedly smaller cross-sectional area than said secondary winding extensions; and a casing for the central portion enclosing said transformer.

5. An electrical heating apparatus comprising v a quick-heating soldering iron including a stepdown transformer having primary and secondary windings, said secondary winding being of pronouncedly greater cross-sectional area than said primary winding, and a detachable tinnable copper heating tip rigidly mounted and held tightly in electrical communication across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area throughout than the secondary winding.

6. An electrical heating apparatus comprising a quick-heating soldering iron including a stepdown transformer having primary and secondary windings, said secondary winding being of pronouncedly greater cross-sectional area than said primary winding, and a detachable copper heating tip rigidly mounted and held tightly in electrical communication across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area throughout than the secondary winding, the pronouncedly smaller crosssection of said heating tip producing substantial thermal resistance in said heating tip between the mid-point thereof and the secondary winding to concentrate heating in said tip in the region of said mid-point.

7. An electrical heating apparatus comprising a quick-heating soldering iron including a stepdown transformer having primary and secondary windings, said secondary winding being of pronouncedly greater cross-sectional area than said primary winding, and a detachable copper heat:

ing tip rigidly mounted and held tightly in electrical communication across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area throughout than the secondary winding, the pronouncedly smaller crosssection of said copper heating tip producingsubstantial thermal resistance in said heating tip between the mid-point thereof and the secondary winding to [substantially intensify heating of said tip in the region of said mid-point.

8. An electrical heating apparatus comprising a quick-heating soldering iron including a stepdowntransformer having primary and secondary windings, saidsecondary winding being of pro; nouncedly greater cross-sectional area than said primary winding, and a detachable copper heating tip rigidly mounted .and held tightly in elec- 9, An electrical heating apparatus comprising a quick-heating soldering iron including a steptransformer having primary and secondary windings, said. secondary winding being of pronouncedlygreatercross-sectional area than said primary winding, and a detachable copper heating tip rigidly mounted and held tightly in electrical communication across the secondary winding, said heating tip being of pronouncedly smaller cross-sectional area throughout than the secondary winding, said copper heating tip having substantial thermal resistance therein produced y the pronouncedly smaller cross-section thereof anddisposed between the mid-point of said tip and the secondary winding to substantially intensify heating therein in the region of said midpoint.

10. A quick-heating soldering iron having spaced end portions. a center portion therebetween, a' step-down transformer having primary and secondary windings in thecenter portion, a pistol-grip containing an og-on trigger switch on one of said end portions, said switch for controlling said transformer, spaced secondary winding extensions fixed in the other of said end portions, and a detachable substantially V-shaped copper wire heating tip held tightly in electrical communication with the secondary winding ea:- tensions and projecting from the last-mentioned end portion, said heating tip being of pronouncedly smaller cross-sectional area throughout than said secondary winding extensions, the electrical resistance of said copper heating tip varying in direct proportion to variations in the windings, said secondary winding'being of pronouncedly greater cross-sectional area than said primary winding, and a casing having a portion enclosing said transformer and a pistol-grip portion, an on-ofl' trigger switch in said pistol-grip portion for selectively compieting the circuit through the primary winding, and switch being normally spring' biizsed to open-circuit position, said secondary winding having forward extension leads," and a tinnable heating tip of generally'hairpin-lilce conflg'uratiommountin'g means therefor comprising openings in said secondary extensions and threaded members cooperating therewith for detachably and rigidly mounting said tip to be held tightly in electrical com- 8 REFERENCES CITED The following references are of record in the file of this patent or the original patent:

Number 445.648

Number ,8 UNITED sums m'mm's- Name Date Cannell Feb. 8, 1891 Sancho 1 May 31, 1892 Coflln Dec. 27-, 1802 Comn Nov. 7, .1093 Snyder et a1. Aug. 25, 1896 Munger et 8.1 July 11, 1916 Santschi July 17, 1928 Gran Feb. 17, 1931 Hello Apr. 21, 1931 Hello July 28, 1931 Meyer Dec. 14, 1937 Hanson Jan. 2. 1940 Brook Sept. 3, 1940 Weller Apr. 22, 1952 FOREIGN PATENTS Country Date France June 24, 1035 France Dec. 16, 1038 

